User Defined Protocol for Zero-Added-Jitter and Error Free Transmission of Layer-2 Datagrams Across Lossy Packet-Switched Network Links

ABSTRACT

A zero-added-jitter protocol for transmission of datagrams over packet-switched networks between two or more connected microprocessor devices with negligible packet delay variation and negative acknowledgment datagram recovery. A method for the analysis and preservation of the instantaneous bitrate and packet spacing provides for the output of the datagrams to a network facing provider edge device matching in timing and inter-packet spacing, that which was originally received, along with a pre-configured time-delay for error correction. Additional embodiments provide duplication of path for reduction of re-requests; the splitting of path for faster transport between transmitter and receiver; encryption for more secure transport between transmitter and receiver; compression for more efficient transport between transmitter and receiver; and encryption and compression, for more secure, efficient transport between transmitter and receiver.

FIELD OF THE INVENTION

The invention relates to the field of data communications via packet switched networks.

BACKGROUND OF THE INVENTION

Various User Defined Protocols (UDP) enable the transport of layer-2 datagrams, primarily but not limited to carrying media streams across packet switched networks. Prior art is limited to packet recovery, re-request mechanisms, and buffering; to management of the number of re-requests; or to dynamically adjusting the size of the buffer, the latter method having been developed specifically for voice communications. These mechanisms correct for packet loss due to congestion, router queue overflow or other transmission errors sometimes present when sending large bursts of data. Prior art lacks means to restore the original instantaneous bitrate and inter-packet spacing which are lost when buffering.

Failure to restore the original instantaneous bitrate and inter-packet spacing may lead to increased jitter, the irregular movement, variation, or unsteadiness that is perceived when watching, measuring or listening to such a media or data stream. All means cited in the prior art attempt to ensure the datagrams are as complete as possible, subject to an upper limit of the maximum time period that a buffer may hold. They do not attempt to restore the original instantaneous bitrate and inter-packet spacing. Prior art notes that transmission re-requests may in fact add jitter, and attempts to minimize the perception of it by time-stamping, leaving it to the receiver to make adjustments.

SUMMARY OF THE INVENTION

In this invention, we present a method for the preservation of the instantaneous bitrate and packet spacing for transmission with zero-added-jitter, even while adding a pre-configured time delay for error correction.

A first embodiment of the present invention analyzes the original instantaneous bitrate and inter-packet spacing of the original transmitted datagrams, calculates a virtual packet size based on the bytes required to fill a private wire or set of point-to-point virtual circuits of predefined bitrate capacity set by the user, in a time equal to the inter-packet interval between the current and previous incoming datagrams, and in addition provides for packet recovery, a re-request mechanism, and buffering. A transmitter transmits the datagrams from one point in a packet switched network to another. The receiver then outputs datagrams to a network facing provider edge device with zero-added-jitter, because the output matches in timing and inter-packet spacing, that which was originally received, along with a pre-configured time-delay for error correction.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a first embodiment;

FIG. 2 is a schematic diagram illustrating a second embodiment;

FIG. 3 is a schematic diagram illustrating a third embodiment;

FIG. 4 is a schematic diagram illustrating a fourth embodiment;

FIG. 5 is a schematic diagram illustrating a fifth embodiment, and

FIG. 6 is a schematic diagram illustrating a sixth embodiment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In a first embodiment 1 of the present invention, shown in FIG. 1, the transmitter datagram processing module 1 a contains a virtual packet size calculator 1 d which analyzes the original instantaneous bitrate and inter-packet spacing of the incoming packets which arrive via a network facing provider edge device 1 c. It calculates a virtual packet size based on the bytes required to fill a private wire or set of point-to-point virtual circuits of predefined bitrate capacity set by the user, in a time equal to the inter-packet interval between the current and previous incoming datagrams. It tags the datagram with that calculated virtual packet size. A counter unit 1 b had previously tagged the datagram with a sequence number. The datagram, now tagged with the two additional pieces of information, is sent out to a virtual provider edge device 1 f, and a copy stored in the datagram storage module 1 f which is part of the negative acknowledgement processing module 1 e.

At a receiver datagram processing module 1 i side of the VLPS (Virtual Private LAN Service) 1 h, the datagram arrives through a virtual provider edge device 1 j at the datagram parser module 1 k. The datagram parser module 1 k examines the sequence, and discards duplicates. If not a duplicate, it is forwarded to a datagram buffer module 1 l, and a copy sent to a negative acknowledgement request module 1 p.

For the datagrams stored in the datagram buffer module, a gate 1 m reads the tagged virtual packet size, and with it, releases the datagrams on a first-in, first-out basis using the following algorithm:

-   -   1. A total value of virtual bytes (TVVB) is calculated for the         entire buffer using the sum of all the virtual packet sizes for         all the packets stored in it.     -   2. A fixed virtual total target buffer size (VTTBS) is         calculated using the bitrate of the private wire (BPW) and the         desired delay (DD) using this formula: VTTBS=BPW         (bytes/seconds)×DD (seconds)     -   3. The gate will output datagrams to the counter removal unit (1         n) at a rate that keeps TVVB=VTTBS.

This produces a rate and inter-packet spacing matching the incoming inter-packet spacing as calculated by the virtual packet size calculator 1 d, while at the same time provides a fixed precise delay. The counter removal unit 1 n removes the tags and the packets are released to the network facing edge provider 1 o.

By having matched the rate and inter-packet spacing, embodiment 1 has transported the datagrams without additional jitter, while adding a buffer in which to request and correct errors in transmission.

For the datagrams that had been copied and forwarded to a negative acknowledgement request module 1 p, should that module detect a packet missing from the sequence, it sends a negative acknowledgement notification via the virtual provider edge devices 1 f and 1 j and VPLS tunnel 1 h to a retransmit module 1 g in the transmitter datagram processor module 1 a. The retransmit module 1 g retrieves the specific packet from the datagram storage module, and resends it via the virtual provider edge devices 1 f and 1 j and VPLS tunnel 1 h to a datagram parser module 1 k in a receiver datagram processing module 1 i, which then adds it to a datagram buffer module 1 l.

A second embodiment 2 of the invention, seen in FIG. 2, provides the same process and benefits as that of first embodiment 1, and adds a data duplication module 2 d and redundant path 2 r and 2 s between transmitter and receiver to reduce re-requests.

A third embodiment 3 of the invention, seen in FIG. 3, provides the same process and benefits as that of first embodiment 1, and adds a data splitting module 3 d and a split path 3 r and 3 q between transmitter and receiver to transmit up to twice as fast.

A fourth embodiment 4 of the invention, seen in FIG. 4, provides the same process and benefits as that of first embodiment 1, and adds a data encryption module 4 e and a data decryption module 4 m, providing greater security and privacy for transmission between the transmitter datagram processing module and the receiver datagram processor module.

A fifth embodiment 5 of the invention, seen in FIG. 5, provides the same process and benefits as that of first embodiment 1, and adds a data compression module 5 e and a data decompression module 5 m, providing more efficient transmission between the transmitter datagram processing module 5 b and the receiver datagram processor module 51.

A sixth embodiment 6 of the invention, seen in FIG. 6, provides the same process and benefits as that of the first embodiment 1, and adds a data encryption module 6 f, a data decryption module 6 n, a data compression module 6 e and a data decompression module 6 o, providing greater security, privacy and efficiency for transmission between the transmitter datagram processing module 6 b and the receiver datagram processor module 6 m. 

I claim:
 1. A process of operating two or more connected microprocessor devices of a known type so that the connected microprocessor devices may execute the transmission of datagrams over packet-switched networks with negligible packet delay variation and negative acknowledgment datagram recovery, said process comprising: (a) a transmitter datagram processing module including (i) a counter unit to tag each incoming datagram from a network facing provider edge device with a sequential incremental number, (ii) a virtual packet size calculator to tag additional information in the datagram header, specifically, the virtual packet size, a number calculated as the bytes required to fill a private wire or set of point-to-point virtual circuits of predefined bitrate capacity set by the user, in a time equal to the inter-packet interval between the current and previous incoming datagrams, and send said tagged datagram to a virtual provider edge device and VPLS tunnel, and (iii) a negative acknowledgment processing module including (A) a datagram storage module to store a copy of said tagged datagrams received from said virtual packet size calculator, and (B) a retransmit module to fetch one or more of said datagrams from said datagram storage module upon a negative acknowledgment notification and to retransmit said tagged datagrams via said virtual provider edge device; (b) a receiver datagram processing module comprising including (i) a datagram buffer module to hold one or more tagged datagrams, (ii) a datagram parser module to receive tagged datagrams from said transmitter datagram processing module via a virtual provider edge device, and insert them into said datagram buffer module based on said sequential incremental number, and to discard them if duplicate, (iii) a gate to maintain said datagram buffer module at a limited size by the controlled release of said received tagged datagrams on a first-in, first-out basis, at a rate and inter-packet spacing matching the incoming inter-packet spacing, the gate having utilized the said private wire size and said virtual packet size in its calculations, to said transmitter datagram processing module, with a fixed delay of user determined size in conjunction with said datagram buffer module, (iv) a counter removal unit to remove said sequential tags and said virtual packet size information from said tagged datagrams before release to a network facing provider edge device, (v) a negative acknowledgment request module to receive copies of said tagged datagrams from the datagram parser module, to detect lost tagged datagrams based on said sequential incremental number, to send said negative acknowledgment notification upon detection of said lost tagged datagrams to said transmitter datagram processing module.
 2. A process as claimed in claim 1, wherein said transmitter datagram processing module further includes a data duplication module to duplicate said tagged datagrams, so that they may be transmitted separately.
 3. A process for the transmission of datagrams over packet-switched networks as claimed in claim 1 wherein said transmitter datagram processing module further includes a data splitting module to split said tagged datagrams, so that they may be transmitted separately.
 4. A process as claimed in claim 1, 2, or 3, wherein said transmitter datagram processing module further includes a data encryption module to encrypt said tagged datagrams so that they may be transmitted encrypted, and wherein said receiver datagram processing module further includes a data decryption module to decrypt said tagged and encrypted datagrams.
 5. A process as claimed in claim 1, 2, or 3, wherein said transmitter datagram processing module further includes a data compression module to compress the said tagged datagrams, so that they may be transmitted compressed, and wherein said receiver datagram processing module further includes a data decompression module to decompress the said tagged and compressed datagrams.
 6. A process as claimed in claim 1, 2 or 3, wherein said transmitter datagram processing module further includes a. a data compression module to compress the said tagged datagrams, so that they may be transmitted compressed, and b. a data encryption module to encrypt the said tagged and compressed datagrams so that they may be transmitted encrypted and compressed, and wherein said receiver datagram processing module further includes a. a data decryption module to decrypt the said tagged, encrypted and compressed datagrams, and b. a data decompression module to decompress the said tagged and compressed datagrams. 